The present invention generally relates to a storage system group configured by one or more storage systems, and more particularly to data backup.
For example, the snapshot function and journal function are known as functions of a storage system.
The snapshot function holds an image of a certain logical volume at a certain point in time (for example, the point in time at which a snapshot acquisition request was received from the host). Executing the snapshot function regularly makes it possible to intermittently acquire replications (backups) of data inside a logical volume. Further, when the snapshot function is used, it is possible to restore the logical volume of the point in time at which the snapshot was acquired.
When write data is written to a logical volume specified by a write command from the host computer, the journal function creates data (a journal) comprising this write data and control information related to the writing thereof, and stores the created journal.
Japanese Patent Application Laid-open No. 2005-18738 discloses a recovery process, which is executed at a point in time other than the point at which a snapshot was created by writing the write data inside a journal to a snapshot acquired via the snapshot function.
Japanese Patent Application Laid-open No. 2007-80131 has a disclosure for switching a snapshot and a journal.
Japanese Patent Application Laid-open No. 2007-133471 has a disclosure for manipulating a snapshot restore volume.